Last night I had to re-install Firefox because I couldn't connect with internet

Since last night and up to now I've tried multiple solutions, however, the re-installed Firefox is not working as previously (just yesterday afternoon) - for example, on the left all my screens are partly hidden - also desktop doesn't show up, then search is not responding correctly and adding to the taskbar is practically as good as out of order. Unfortunately I've also detected that the re-installment come with demand of using - bing - which I do not use, as I'm very familiar with Firefox & Google which I've been using at least for over a decade an are very Happy with. However - bing - kept popping up, until finally today/afternoon the facility to dismiss - bing - suddenly & fanally was available so it got by-passed, although as much as possible, as it rears its presence still somehow every now & then. On top of all this, I also don't have Desktop